Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator

Shumiya, Nana; Hossain, Md. Shafayat; Yin, Jia-Xin; Wang, Zhiwei; Litskevich, Maksim; Yoon, Cheol Hwan; Li, Yongkai; Yang, Ying; Jiang, Yanli; Cheng, Guangming; Lin, Yen-Chuan; Zhang, Qi; Cheng, Zi-Jia; Cochran, Tyler A.; Multer, Daniel; Yáng, Xiàn; Casas, Brian; Chang, Tay-Rong; Neupert, Titus; Yuan, Zhujun; Jia, Shuang; Lin, Hsin; Yao, Nan; Balicas, Luis; Zhang, Fan; Yao, Yugui; Hasan, M. Zahid

doi:10.1038/s41563-022-01304-3

Cited by 69 publications

(46 citation statements)

References 40 publications

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“…It should be noted that the gap value shows a weak dependence with the change in temperature, preserving the quantum spin Hall gap of ∼0.2 eV and consequently promising the potential application of this material in electronic and spintronic devices to overcome thermal perturbations at room temperature. The temperature-dependent ARPES results are consistent with the temperature-dependent STS mapping results, where the TES survives at room temperature due to the large energy gap and atomically sharp edge [28].…”

Section: Surface Electronic Structure Of Bi 4 Br 4 Single Crystalsupporting

confidence: 84%

“…Due to the lack of spatial resolution for ARPES methods, the origin of the edge states observed in their experiments needs to be further confirmed by allying with other experimental techniques. Using the STM/STS methods with high spatial resolution, Shumiya et al [28] studied the DOS difference at the two kinds of edges due to the possible hybridization of edge states between two adjacent layers.…”

Section: Hotis: Bulk Bismuth α-Bi 4 Brmentioning

confidence: 99%

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Advances in bismuth-based topological quantum materials by scanning tunneling microscopy

Zhang

et al. 2022

Mater. Futures

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Topological quantum materials (TQMs) have attracted intensive attentions recent years in the area of condensed matter physics due to their novel topologies and the promising application in quantum computing, spin electronics, and next generation of integrated circuits. The scanning tunneling microscope/spectroscope (STM/STS) is regarded as a powerful technique to characterize the local density of state with atomic resolution, which is ideally dedicated to the measurements of bulk-boundary correspondence of TQMs. In this review, recent research on the bismuth-based TQMs, including quantum-spin Hall insulators, three-dimensional weak topological insulators, high-order topological insulators, topological Dirac semimetals, and dual topological insulators, by STM/STS is focused on. The efficient methods of the modulation of the topological properties of the TQMs are introduced, such as interlayer interaction, thickness variation, and local electric field perturbation, and finally, the challenges and prospects for this field are discussed.

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Section: Surface Electronic Structure Of Bi 4 Br 4 Single Crystalsupporting

confidence: 84%

Section: Hotis: Bulk Bismuth α-Bi 4 Brmentioning

confidence: 99%

Advances in bismuth-based topological quantum materials by scanning tunneling microscopy

Zhang

et al. 2022

Mater. Futures

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“…By calculating the electronic structure evolution with variable interlayer distance, we demonstrate that a topological phase transition from the STI phase to the WTI phase can be achieved by a weakened interlayer coupling. Similar concepts have recently been reported in quasi-1D bismuth halide system [33][34][35] and TaSe 3 . [36,37] More importantly, recent intriguing discoveries in 2M-TMDs, such as the coexistence of TSSs and superconductivity, [29,38,39] signatures of zero Majorana modes [40] and Pauli-limit violated superconductivity, [41] them not only ideal for fundamental research, but also promising materials for novel applications.…”

Section: Introductionsupporting

confidence: 87%

“…Bulk topological materials consisting of QSH layers have been theoretically proposed and experimentally realized in various compounds. Experimental signatures of topological edge states have been observed on the bulk crystal stepping edges of WTe 2 , [49] transition-metal pentatelluride ZrTe 5 and HfTe 5 , [50,51] bismuth halide Bi 4 I 4 and Bi 4 Br 4 , [33][34][35]52,53] transition-metal tritelluride TaSe 3 , [36,37] and CaSn, [54] however, experimental confirmations of the QSH states in the monolayer forms are limited to very few materials. [55] 2M-TMD family and their sister compounds WTe 2 and MoTe 2 stand out for the following reasons.…”

Section: Discussionmentioning

confidence: 99%

Topology Hierarchy of Transition Metal Dichalcogenides Built from Quantum Spin Hall Layers

Fang

et al. 2023

Advanced Materials

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The evolution of the physical properties of 2D material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'‐phase transition metal dichalcogenides (1T'‐TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal 2D building blocks of various 3D topological phases. However, the stacking geometry has been previously limited to the bulk 1T'‐WTe2 type. Here, the novel 2M‐TMDs consisting of translationally stacked 1T'‐monolayers are introduced as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization‐dependent angle‐resolved photoemission spectroscopy as well as first‐principles calculations on the electronic structure of 2M‐TMDs, a topology hierarchy is revealed: 2M‐WSe2, MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M‐WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M‐TMDs. It is proposed that 2M‐TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with 2D materials.

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“…Such systems, known as higher-order topological insulators (HOTIs) have attracted great interest since their discovery. HOTI phases are now ubiquitous in condensed matter [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], metamaterial [42][43][44], and photonic [45][46][47][48][49][50][51][52][53][54] systems.…”

Section: Introductionmentioning

confidence: 99%

Effective action approach to the filling anomaly in crystalline topological matter

Rao¹,

Bradlyn²

2023

Preprint

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In two dimensions, magnetic higher-order topological insulators (HOTIs) are characterized by excess boundary charge and a compensating bulk "filling anomaly." At the same time, without additional noncrystalline symmetries, the boundaries of two-dimensional HOTIs are gapped and featureless at low energies, while the bulk of the system is predicted to have a topological response to the insertion of lattice (particularly disclination) defects. Until recently, a precise connection between these effects has remained elusive. In this work, we provide a unifying field-theoretic description for the bulk and boundary response of magnetic HOTIs. By focusing on the low-energy description of the gapped boundary of a HOTI, we show that the boundary charge and filling anomaly arise from the gravitational "Gromov-Jensen-Abanov" (GJA) response action first introduced in [Phys. Rev. Lett. 116, 126802 (2016)] in the context of the quantum Hall effect. As in quantum Hall systems the GJA action cancels apparent anomalies associated with bulk response to disclinations, allowing us to derive a concrete connection between the bulk and boundary theories of HOTIs. We show how our results elucidate the connection between higher order topology and geometric response both in band insulators, and point towards a new route to understanding interacting higher order topological phases.

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Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator

Cited by 69 publications

References 40 publications

Advances in bismuth-based topological quantum materials by scanning tunneling microscopy

Advances in bismuth-based topological quantum materials by scanning tunneling microscopy

Topology Hierarchy of Transition Metal Dichalcogenides Built from Quantum Spin Hall Layers

Effective action approach to the filling anomaly in crystalline topological matter

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